If, for example, an interviewee said in all seriousness "I want to shoot all dogs and make the poor eat their babies" would you expect the interviewer to go go "Hmmm very interesting. Why do you think that?"
No.
It is vital that interviewers challenge the subject. Especially when they say something profoundly ludicrous or disturbing. Otherwise they might has well just be in PR.
Saying "Well, our listeners can decide for themselves" is a cowardly cop-out.
You might not be able to change the interviewee's mind but you can sure as hell send social signals to your audience that you condemn their views or think they're ludicrous.
Case in point - why are you trying to change my mind here? You're pushing back because you want to signal to others that my point of view is incorrect. That sort of basic interrogation seems completely missing in (especially American) media.
Why wouldn't you do the same if I said something outrageously offensive in public?
Actually yes if a interviewee said something like that I’d like to know why they’re saying that because it doesn’t make sense to me!
Sometimes it helps for institutions to point out the the emperor has no clothes. The social reinforcement of norms is hugely influential.
The risk, of course, is that you don't get invited back. That's "The Test" in the post.